1. Field of the Invention
The present invention relates to agricultural machines, and, more particularly, to undercarriages used on such agricultural machines.
2. Description of the Related Art
Agricultural machines may be either self-propelled or towed, and may take many forms. Self-propelled agricultural machines may include tractors, combines, sprayers, windrowers, etc. Towed agricultural machines may include balers, mower-conditioners, gravity wagons, drills, planters, sprayers, etc.
Agricultural balers, as mentioned above, are used to consolidate and package crop material so as to facilitate the storage and handling of the crop material for later use. In the case of hay, a mower-conditioner is typically used to cut and condition the crop material for windrow drying in the sun. In the case of straw, an agricultural combine discharges non-grain crop material from the rear of the combine defining the straw (such as wheat or oat straw) which is to be picked up by the baler. The cut crop material is typically raked and dried, and a baler, such as a large square baler or round baler, straddles the windrows and travels along the windrows to pick up the crop material and form it into bales.
Agricultural balers typically include at least a pair of ground engaging wheels, and may also include additional wheels (e.g., 4 wheels total), depending on the size of the baler. Depending on how the baler is hitched to the prime mover (e.g., tractor), as well as the width and position of the windrow which is to be picked up by the baler, it may be desirable to adjust the width of the wheels to straddle and not compact the windrow. However, if the wheels are placed at a wide wheel stance during operation, it may be necessary to narrow the wheel stance when driving from one field to the other, or on the road, or if the windrow width is different from one field to the other, or for transportation on a truck such that the wheels fit the dimensions of the truck. It may therefore be desirable to provide the baler with an undercarriage allowing the wheel stance to be easily widened or narrowed.
A problem with a baler having an adjustable wheel stance is that when the baler is set with a wide wheel stance, the weight of the baler may slightly bow the axles downward. The axle bowing may be further exaggerated when the baler is loaded with full bales, particularly in the case of a large square baler or large round baler. The wider the wheel stance, the more the axles tend to bow. Bowing of the axles in turn causes the wheels to tip in at the top, which results in excessive wear of the tires.
What is needed in the art is an agricultural machine having an undercarriage allowing the wheels to be easily configured for a wide or narrow wheel stance, while at the same time accommodating a change in wheel angle which may occur as a result of the change in wheel stance.